Transforming Hydroxide-Containing Metal–Organic Framework Nodes for Transition Metal Catalysis

Hydroxide-containing nodes of metal–organic frameworks (MOFs) are converted into single-site heterogeneous transition metal (TM) catalysts with outstanding catalytic performance. Diverse TM complexes can be immobilized on MOF nodes as single-site solid catalysts by direct reactions with hydroxides, through deprotonation and metalation of hydroxides, or via solvothermal deposition. Hydroxide-containing MOF nodes are directly transformed into catalytically active metal hydrides/alkyls and strong Lewis acids through post-synthetic chemical treatments. The tunable electronic and steric properties of MOF node-based catalysts allow the optimization of catalytic activity and selectivity, while active site isolation by the MOF backbones increases catalyst stability. MOF node-based catalysts are used in combination with other catalysts in the MOFs for tandem, cascade, and synergistic catalysis. The abundance and structural diversity of hydroxide-containing secondary building units (SBUs) in metal–organic frameworks (MOFs) have provided unique opportunities for the development of transition metal (TM) catalysts. This minireview surveys the structures of hydroxide-containing SBUs and summarizes recently developed strategies for the generation of catalytically active metal complexes on these SBUs and direct transformation of SBU hydroxides to catalytically active species. The applications of SBU-based catalysts in various organic transformations are also discussed, along with comparisons with homogeneous benchmarks. Systematic studies of the conversion of SBUs to catalytically active species will reveal structure–reactivity relationships in this class of MOF catalysts and provide structural and functional models for traditional heterogeneous catalysts. Structure-based optimization of SBU-based catalysts promises to lead to highly efficient and low-cost novel TM catalysts with important roles in green chemistry and sustainability. The abundance and structural diversity of hydroxide-containing secondary building units (SBUs) in metal–organic frameworks (MOFs) have provided unique opportunities for the development of transition metal (TM) catalysts. This minireview surveys the structures of hydroxide-containing SBUs and summarizes recently developed strategies for the generation of catalytically active metal complexes on these SBUs and direct transformation of SBU hydroxides to catalytically active species. The applications of SBU-based catalysts in various organic transformations are also discussed, along with comparisons with homogeneous benchmarks. Systematic studies of the conversion of SBUs to catalytically active species will reveal structure–reactivity relationships in this class of MOF catalysts and provide structural and functional models for traditional heterogeneous catalysts. Structure-based optimization of SBU-based catalysts promises to lead to highly efficient and low-cost novel TM catalysts with important roles in green chemistry and sustainability. two ligands are eliminated from adjacent metal centers to form a new covalent bond between them. The formal oxidation states of both metal centers decreased by one during the process. a reaction involves two different starting materials with reactive groups. With the aid of a metal catalyst, the two starting materials lose the reactive groups to form a new covalent bond between the remaining fragments. a spectroscopic technique for studying materials with unpaired electrons. EPR provides information on the oxidation and spin states of certain metal centers. a nondestructive X-ray absorption technique for the determination of local molecular structures of various materials, including crystalline and noncrystalline materials. The EXAFS feature is caused by scattering of the photoelectron ejected from the absorbing atom by the photoelectric effect and is fitted with the EXAFS equation to provide information on bonding elements, bond distances, and the coordination geometry of the absorbing element. any substance, such as the H+ ion, that can accept a pair of nonbonding electrons. In other words, a Lewis acid is an electron-pair acceptor. inorganic–organic hybrid crystalline porous materials constructed by the coordination polymerization of metal nodes/clusters and organic linkers to form a repeating, cage-like structure with a large internal surface area. MOFs belong to a subclass of coordination polymers or coordination networks that have been explored extensively since the 1980s. molecular metal complexes and clusters as subunits of MOFs whose coordination with multiple organic linkers lead to the transformation of these fragments into extended porous networks. solid catalytic materials with uniform, isolated, and molecularly defined catalytic centers. a catalytic approach involving the d-block elements, which include groups 4 to 10 metals in the periodic table.